The present invention relates to a device for measuring an amount of rubber contained between a pair of rolls arranged, for example in a heat treatment roll, a calender roll, etc.
It is sometimes desired to measure an amount of rubber banked, that is constrained between a pair of rolls in certain applications such as a heat treatment roll, a calender roll, or the like. This is because, for example, in a heat treatment roll, when the rubber which is now being heat treated is exchanged with another type of rubber, it is necessary to determine the feeding timing of the second type of rubber on the basis of the amount of the retained or banked rubber in order to reduce rubber remixing. In the case of a calender roll, in manufacturing a sheet-like material, it is necessary to cause an extruder for feeding resin to the calender roll to be subject to feedback control on the basis of the amount of the banked resin.
A device for measuring a banked amount of rubber for calender roll operation is disclosed in Japanese Patent Application Laid-Open No. 132072/1977. In this device, contrast is provided by irradiating light to resin banked between a pair of rolls from the slantingly upper forward direction of the resin by a lighting device. The irradiated resin is photographed by a camera disposed in front of the resin.
In treating rubber by using such a measuring device, however, the irradiated light is reflected from both the surfaces of the banked rubber and the rear roll, so that there is a problem in that it is difficult to clearly distinguish the boundary between the rubber and the rear roll. On the other hand, it can be theoretically considered to arrange a light device, banked resin and a camera substantially on a straight line, to make the light irradiate on the banked resin as well as directly imfringe on the camera. In such an arrangement, however, "blooming" may occur in the camera image due to the directly incident light. The boundary of the resin is vague to discern given this optical problem.